1. Field of the Invention
This invention relates to an apparatus and a method for reading data signals from an optical disc, and more particularly to an apparatus and a method of reading data signals from a high-density optical disc and cancelling crosstalk.
2. Description of the Prior Art
There is known a problem called "crosstalk" which occurs when data signals recorded on an optical disc is to be read out. Crosstalk is a phenomenon that a read-out data signal of adjacent tracks are mixed into a read-out data signal of a target track to be read-out because a diameter of reading light beam spot is larger than a width of each tracks. In order to cancel the crosstalk, it is conventionally known a method of irradiating the light beam onto the target track and the tracks adjacent thereto, calculating the crosstalk component from the read-out data signals according to various computing algorithms, and subtracting it from the read-out data signal of the target track.
However, in order to increase an accuracy of crosstalk cancellation by the conventional method, calculation circuits must be designed more complicated and hence an operation time of calculating an crosstalk cancelling coefficient becomes longer. Further, recently, minimization of track width has been examined so as to further increase recording density of an optical disc. However, if the track width is reduced without minimizing the spot diameter of light beam, crosstalk component will be increased, and therefore it becomes difficult to sufficiently cancel the crosstalk component and accurately obtain the recorded data signal.